The present invention generally relates to an information recording/reproducing apparatus, an information recording/reproducing method, and a transmission medium. In particular, the present invention relates to an information recording/reproducing apparatus, an information recording/reproducing method, and an information transmission medium that minimize damage to an information recording medium by recording a predetermined pattern when recording part of information in an overlapping manner.
Generally, two types of optical discs are currently available; a ROM disc dedicated to only reading information from it and a RAM disc allowing both recording (or writing) data to it and reproducing data from it. In the ROM disc, data is continuously recorded without interruption. Consequently, the ROM disc allows tracking control by DPD (Differential Phase Detection) that uses the edges along the length of each mark formed on the disc (it should be noted that the mark referred to herein includes a pit formed by a physical concavity).
As for the RAM disc, when no data is recorded on it, an area of a state in which no mark is formed on a data track (namely, there is no edge along the length of the pit) is formed. An optical disc apparatus for recording data to a RAM disc and reproducing data recorded on it normally uses a groove formed on the RAM disc so that tracking can be executed in a state in which no data is recorded. Tracking is executed by use of a sidewall of this groove (or a data track sidewall). With the ROM disc, which has no groove formed, the edge along the width of each mark serves as the sidewall of the groove. Therefore, the ROM disc can be loaded on an optical disc device designed for the RAM disc to execute tracking control for data reproduction.
However, loading a RAM disc having at least a section with no data recorded into an optical disc apparatus dedicated to the ROM disc and executing tracking by DPD make it difficult to correctly drive the RAM disc because this apparatus cannot execute tracking control in the section with no data recorded. To make the optical disc apparatus dedicated to the ROM disc also drive the RAM disc correctly, no section with data not recorded must be formed on the RAM disc.
In the RAM disc, data is recorded on an ECC block basis. When an ECC block is followed by another ECC block, the data of the preceding ECC block and the data of the succeeding ECC block are recorded in a partially overlapping manner. This prevents the forming of a section in which no data is recorded due to jitters or the like between these ECC blocks.
Namely, in the conventional RAM disc, a record mark having a length of 4 T and an erase mark having a length of 4 T are alternately recorded in the section in which data are recorded in an overlapping manner as shown in FIG. 13.
As described, the RAM disc is recorded with data in a partially overlapping manner. Consequently, repeatedly rewriting data doubles the number of times data are rewritten in the overlapping section over the number of times data are rewritten in other sections. This lowers the reliability in data rewriting in that section.
The section in which data are recorded in an overlapping manner normally provides an APC (Automatic Power Control) area. The laser power for data recording is adjusted based on the state in which data are written in that section. Consequently, if that section is damaged, it becomes difficult to set the laser power correctly.
Further, an OPC (Optional Power Control) area is formed on the innermost periphery of the optical disc. The APC area is also formed in this OPC area. The light intensity at the time when the use environment of the optical disc apparatus has changed is adjusted based on the data recording state in the APC area. Consequently, if the APC area is damaged, it becomes difficult to make an adjustment of the light intensity at the time when the use environment of the optical disc apparatus has changed.